A measurement of an ultraviolet dose is used in various fields, for example, ultraviolet dosimeters are used to measure the ultraviolet dose of an object irradiated with ultraviolet radiation from an ultraviolet irradiation system for curing ultraviolet-curable resins.
Commonly known ultraviolet dosimeters are semiconductor photovoltaic devices, which are expensive and not readily portable. Simpler and inexpensive known tools are photochromic cards, which change color reversibly in response to ultraviolet. Although photochromic cards can be used to determine the ultraviolet intensity during irradiation, the cumulative illuimance of ultraviolet cannot be determined.
For example, Patent document 1 proposes a method for measuring cumulative irradiance with allochroic materials. Unfortunately, this method is not suitable for quantitative determination because of insufficient sensitivity.
Also proposed are a method for quantitatively determining ultraviolet dose using photosensitive paper (see Patent document 2) and a method utilizing oxidative coloration of leuco dyes (see Patent document 3). Unfortunately, these methods are intended for recording and are not suitable for measurement of ultraviolet irradiance over a wide range. These methods are also not suitable for measurement of ultraviolet irradiance in a range from 100 to 1,000 mJ/cm2, which is most widely used in manufacturing processes involving the use of ultraviolet curing.